Modeling and Analysis of Shock Impingements on Thermo-Mechanically Compliant Surface Panels

Abstract

Fluid-Thermal-Structural interactions play an important role in the development of high speed vehicles, impacting various sub-disciplines (i.e., aerodynamic, structural, material, propulsion, and control) at the micro, component and/or vehicle scales. This study focuses on the development of a partitioned fluid-thermal-structural procedure aimed at performing a long time record thermo-structural response prediction of surface panels subject to shock impingements. Specific modeling aspects essential to this are reduction of the computational aerothermodynamics to a tractable model, and partitioned timemarching of the fluid-thermal-structural problem. Additional factors considered are: 1) the movement of the shock impingement due to forced motion of a shock generator, 2) panel backpressure, 3) a 140dB random prescribed pressure load to account for pressure fluctuations associated with turbulent boundary layers, and 4) coupled vs. uncoupled fluid-thermal-structural analysis. Results indicate that quasistatic CFD analysis provides a promising means for generating an aerothermodynamic surrogate model. Differences between quasi-static and unsteady models were under 6% for both panel temperature rise and pressure loads for a forced motion analysis. Several studies using the fluid-thermal-structural model are performed, focusing on the differences between the coupled and uncoupled analyses, as well as the role of backpressure on the panel response. The effect of the backpressure to the direction of panel buckling is investigated, and the backpressure required to buckle the panel into the flow is predicted to be ∼10% of free stream higher for the uncoupled model than the coupled model. However, generally differences were minor between the coupled and uncoupled analysis. The inclusion of a 140 dB prescribed pressure load, meant to mimic the effect of turbulent boundary layer loadings, results in negligible temperature differences. However, both the shock motion and this load introduce large amplitude oscillations at the start of the response, followed by relatively small oscillations once the buckling amplitude of the panel becomes significant.

Characterizing the Role of Plasticity in Structural Response to High Speed Flows

“…Note that the thermal model neglects panel deformation. The model has been previously verified 16 through comparisons to results with the thermal solver in Abaqus R .…”

Characterization of Structural Response to Hypersonic Boundary Layer Transition

“…This is carried out by solving a finite element formulation of the transient, two-dimensional (2-D) heat transfer equation with temperature-dependent specific heat and thermal conductivity. 35 The 2-D formulation allows for heat conduction through both the thickness and length of the panel. An adiabatic wall condition is prescribed for each boundary of the panel except the upper surface where the aerodynamic heat flux is applied.…”

Robust Treatment of Temperature Feedback in Aerothermodynamic Models for Fluid-Thermal-Structural Analysis

“…The upper bound of the surface temperature is set to 600 K, which is approximately the total temperature for these flow conditions. The structural deformation of the panel is represented using the first six structural free vibration modes 43 and non-dimensional amplitudes (a * i = ai /h), where h is the thickness of the panel (0.711mm), according to:…”